While various means have been provided for securing nail plates at the junction of the wood members of the truss, it is believed that the use of the heavy C-frames mounted within a carriage which advances the C-frames from one position to another, and to be operated alone or simultaneously, is new with applicant. It was found that applying pressure to the entire nail plate at the bottom and the top of the truss sets the nails a maximum amount within the wood members providing assurance that the joints will be firmly maintained.